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Philosophy of Spiritual Activity
GA 4

VII. Are There Limits to Knowledge?

[ 1 ] We have established that the elements for the explanation of reality are to be taken from the two spheres of perception and thinking. It is due, as we have seen, to our organization that the full totality of reality, including our own selves as subjects, appears at first as a duality. Knowledge overcomes this duality by fusing the two elements of reality, the percept and the concept gained by thinking, into the complete thing. Let us call the manner in which the world presents itself to us, before by means of knowledge it has taken on its true nature, “the world of appearance,” in distinction from the unified whole composed of percept and concept. We can then say: The world is given to us as a duality, and knowledge transforms it into a unity. A philosophy which starts from this basic principle may be called a Monistic philosophy, or Monism. Opposed to this is the theory of two worlds, or Dualism. The latter does not indeed assume that there are two sides of a single reality, which are kept apart merely by our organization, but that there are two worlds absolutely distinct from one another. It then tries to find in one of these two worlds the principles of explanation for the other.

[ 2 ] Dualism rests on a false conception of what we call knowledge. It divides the whole of existence into two spheres, each of which has its own laws, and it leaves these two worlds standing opposite and outside one another.

[ 3 ] It is from a Dualism such as this that there arises the distinction between the object of perception and the thing-in-itself, which Kant introduced into science, and which, to the present day, we have not succeeded in expelling. According to our interpretation, it is due to the nature of our spiritual organization that a particular thing can be given to us only as a percept. Thinking then overcomes this particularity by assigning to each percept its legitimate place in the world as a whole. As long as we determine the separated parts of the cosmos as percepts, we are simply following, in this sorting out, a law of our subjectivity. If, however, we regard all percepts, taken together, merely as one part, and contrast with this a second part, viz., the things-in-themselves, then our philosophy is building castles in the air. We are then engaged in mere playing with concepts. We construct an artificial opposition, but we can gain no content for the second of these opposites, for such a content for a particular thing can be gathered only from perception.

[ 4 ] Every kind of existence which is assumed outside the realm of percept and concept must be relegated to the sphere of unjustified hypotheses. To this category belongs the “thing-in-itself.” It is quite natural that a Dualistic thinker should be unable to find the connection between the world-principle which he hypothetically assumes and the things given in experience. For the hypothetical world-principle itself a content can be found only by borrowing it from the world of experience and shutting one's eyes to the fact of the borrowing. Otherwise it remains an empty concept, a non-concept which has only the form of a concept. In this case the Dualistic thinker generally asserts that the content of this concept is inaccessible to our knowledge. We can know only that such a content exists, but not what it is. In either case it is impossible to overcome Dualism. Even though one were to import a few abstract elements from the world of experience into the concept of the thing-in-itself, it would still remain impossible to reduce the rich concrete life of experience to those few qualities which are, after all, themselves taken from perception. Du Bois-Reymond lays it down that the imperceptible atoms of matter produce sensation and feeling by means of their position and motion, and then comes to the conclusion that we can never find a satisfactory explanation of how matter and motion produce sensation and feeling, for “it is absolutely and for ever unintelligible that it should be other than indifferent to a number of atoms of carbon, hydrogen, and nitrogen, etc., how they lie and move, how they lay and moved, or how they will lie and will move. It .is in no way intelligible how consciousness can come into existence through their interaction.” This conclusion is characteristic of the tendency of this whole trend of thought. Position and motion are abstracted from the rich world of percepts. They are then transferred to the fictitious world of atoms. And then astonishment arises that life cannot be evolved out of this self-made principle borrowed from the world of percepts.

[ 5 ] That the Dualist, working as he does with a completely empty concept of the thing-in-itself, can reach no explanation of the world, follows already from the very definition of his principle which has been given above.

[ 6 ] In any case, the Dualist finds it necessary to set impassable barriers to our faculty of knowledge. The follower of a Monistic world-conception knows that all he needs to explain any given phenomenon in the world is to be found within this world itself. What prevents him from reaching it can be only contingent limitations in space and time, or defects of his organization, i.e., not of human organization in general, but only of his own particular one.

[ 7 ] It follows from the concept of knowledge, as defined by us, that there can be no talk of limits of knowledge. Knowledge is not a concern of the universe in general, but one which men must settle for themselves. Things claim no explanation. They exist and act on one another according to laws which thinking can discover. They exist in indivisible unity with these laws. Our Egohood confronts them, grasping at first only what we have called percepts. However, within our Egohood we find the power to discover also the other part of reality. Only when the I has combined for itself the two elements of reality which are indivisibly bound up with one another in the world, is our thirst for knowledge stilled. The I has then again attained reality.

[ 8 ] The presuppositions for the arising of the act of knowledge thus exist through and for the I. It is the I which sets itself the problems of knowledge. It takes them from thinking, an element which in itself is absolutely clear and transparent. If we set ourselves questions which, we cannot answer, it must be because the content of the questions is not in all respects clear and distinct. It is not the world which sets questions to us, but we who set them.

[ 9 ] I can imagine that it would be quite impossible for me to answer a question which I happened to find written down somewhere, without knowing the sphere from which the content of the question was taken.

[ 10 ] In knowledge we are concerned with questions which arise for us through the fact that a sphere of percepts, conditioned by time, space, and our subjective organization, stands over against a sphere of concepts pointing to the totality of the universe. My task consists in reconciling these two spheres, with both of which I am well acquainted. There is no room here for speaking of limits of knowledge. It may be that, at a particular moment, this or that remains unexplained because, through our place in life, we are prevented from perceiving the things involved. What is not found to-day, however, may be found to-morrow. The limits due to these causes are only transitory, and must be overcome by the progress of perception and thinking.

[ 11 ] Dualism makes the mistake of transferring the opposition of object and subject, which has meaning only within the perceptual realm, to purely fictitious entities outside this realm. Now the distinct and separate things within the perceptual field remain separated only so long as the perceiver refrains from thinking. For thinking cancels all separation and reveals it as due to purely subjective conditions. The Dualist, therefore, transfers to entities behind the percepts determinations which, by themselves, have no absolute, but only relative, validity. He thus divides the two factors concerned in the process of knowledge, viz., percept and concept, into four: (1) the object in itself; (2) the percept which the subject has of the object; (3) the subject; (4) the concept which relates the percept to the object in itself. The relation between subject and object is “real”; the subject is really (dynamically) influenced by the object. This real process is supposed not to appear in consciousness. But it is said to evoke in the subject a response to the stimulation from the object. The result of this response is said to be the percept. This, at length, is supposed to appear in consciousness. The object is thought to have an objective (independent of the subject) reality, the percept a subjective reality. This subjective reality is said to be referred by the subject to the object. This latter reference is called an ideal one. Dualism thus divides the process of knowledge into two parts. The one part, viz., the production of the perceptual object by the thing-in-itself, he conceives of as taking place outside consciousness, whereas the other, the combination of percept with concept and the letter's reference to the thing-in-itself, takes place, according to him, within consciousness.

With such presuppositions, it is clear why the Dualist regards his concepts merely as subjective representatives of what lies before his consciousness. The objectively real process in the subject by means of which the percept is produced, and still more the objective relations between, things-in-themselves, remain for the Dualist inaccessible to direct knowledge. According to him, man can get only conceptual representatives of the objectively real. The bond of unity of things which connects them with one another, and also objectively with the individual spirit (as things-in-themselves) of each of us, lies beyond our consciousness in a Being in itself of whom, once more, we may have in our consciousness merely a conceptual representative.

[ 12 ] The Dualist believes that the whole world would be dissolved into a mere abstract scheme of concepts, did he not posit real connections beside the conceptual ones. In other words, the ideal principles which thinking discovers seem too airy for the Dualist, and he seeks, in addition, “real principles” with which to support them.

[ 13 ] Let us examine these real principles a little more closely. The naive man (Naive Realist) regards the objects of external experience as realities. The fact that his hands can grasp, and his eyes see these objects, is for him sufficient proof of their reality. “Nothing exists that cannot be perceived” is, in fact, the first axiom of the naive man; and it is held to be equally valid in its converse: “Everything which can be perceived exists.” The best proof for this assertion is the naive man's belief in immortality and in ghosts. He thinks of the soul as a fine kind of sensible matter which, in special circumstances, may actually become visible to the ordinary man (naive belief in ghosts).

[ 14 ] In contrast with this, his real world, the Naive Realist regards everything else, especially the world of Ideas, as unreal, or “merely ideal.” What we add to objects by thinking is merely thoughts about the objects. Thought adds nothing real to the percept.

[ 15 ] But it is not only with reference to the existence of things that the naive man regards sense-perception as the sole proof of reality, but also with reference to the occurrences (processes). A thing, according to him, can act on another only when a force actually present to perception issues from the one and seizes upon the other. The older physicists thought that very. fine kinds of substances emanate from the objects and penetrate through the sense-organs into the soul. The actual seeing of these substances is impossible only because of the coarseness of our sense-organs relatively to the fineness of these substances. In principle, the reason for attributing reality to these substances was the same as that for attributing it to the objects of the sensible world, viz., their form of existence, which was conceived to be analogous to that of sense reality.

[ 16 ] The self-contained character of that which is of the nature of thought is not regarded by the naive mind as real in the same sense. An object conceived “merely in Idea” is regarded as a chimera until sense-perception can furnish conviction of its reality. In short, the naive man demands, in addition to the ideal evidence of his thinking, the real evidence of his senses. In this need of the naive man lies the ground for the origin of primitive forms of the belief in revelation. The God who is given through thinking remains always a God merely “thought.” The naive consciousness demands that God should manifest Himself in ways accessible to sense-perception. God must appear in the flesh, and little value is attached to the testimony of thinking, but only to the divine nature being proved by the changing of water into wine in a way which can be testified by the senses.

[ 17 ] Even knowledge itself is conceived by the naive man as a process analogous to sense-perception. Things, it is thought, make an impression on the soul, or send out images which enter through our senses, etc.

[ 18 ] What the naive man can perceive with his senses he regards as real, and what he cannot thus perceive (God, soul, knowledge, etc.) he regards as analogous to what he perceives.

[ 19 ] On the basis of Naive Realism, science can consist only in an exact description of the content of perception. Concepts are only means to this end. They exist to provide ideal counterparts of percepts. For the things themselves they do not matter. For the Naive Realist only the individual tulips, which we see or can see, are real. The Idea of the tulip is to him an abstraction, the unreal thought-picture which the soul combines for itself out of the characteristics common to all tulips.

[ 20 ] Naive Realism, with its fundamental principle of the reality of all perceived things, contradicts experience, which teaches us that the content of percepts is of a transitory nature. The tulip I see is real to-day; in a year it will have vanished into nothingness. What persists is the species “tulip.” This species is, however, for the Naive Realist “merely” an Idea, not a reality. Thus this theory of the world finds itself in the position of seeing its realities arise and perish, while that which, by contrast with its realities, it regards as unreal, endures. Hence Naive Realism is compelled to acknowledge the existence of something ideal by the side of percepts. It must include within itself entities which cannot be perceived by the senses. In admitting them, it escapes contradicting itself by conceiving their existence as analogous to that of objects of sense. Such hypothetical realities are the invisible forces by means of which the objects of sense-perception act on one another. Another such reality is heredity, the effects of which survive the individual, and which is the reason why from the individual a new being develops which is similar to it, and by means of which the species is maintained. The life-principle permeating the organic body, the soul, is another such reality which the naive mind is always found conceiving in analogy to sense-realities. And, lastly, the Divine Being, as conceived by the naive mind, is a reality of this kind. This Being is thought of as acting in a manner exactly corresponding to that which we can perceive in man himself, i.e., the Deity is conceived anthropomorphically.

[ 21 ] Modern Physics traces sensations back to processes of the smallest particles of bodies and of an infinitely fine substance, called ether, or the like. What we experience, e.g., as warmth is a movement of the parts of a body which causes the warmth in the space occupied by that body. Here again something imperceptible is conceived on the analogy of what is perceptible. Thus, the perceptible analog to the concept “body” is, say, the interior of a room, shut in on all sides, in which elastic balls are moving in all directions, impinging one on another, bouncing on and off the walls, etc.

[ 22 ] Without such assumptions the world of Naive Realism would collapse into a disconnected chaos of percepts, without mutual relations, and having no unity within itself. It is clear, however, that Naive Realism can make these assumptions only by an inconsistency. If it would remain true to its fundamental principle, that only what is perceived is real, then it ought not to assume a reality where it perceives nothing. The imperceptible forces of which perceptible things are the bearers are, in fact, illegitimate hypotheses from the standpoint of Naive Realism. And because Naive Realism knows no other realities, it invests its hypothetical forces with perceptual content. It thus transfers a form of existence (the perceptible existence) to a sphere where the only means of making any assertion concerning such existence, viz., sense-perception, is lacking.

[ 23 ] This self-contradictory theory leads to Metaphysical Realism. The latter constructs, beside the perceptible reality, an imperceptible one which it conceives on the analogy of the former. Metaphysical Realism is, therefore, of necessity Dualistic.

[ 24 ] Wherever the Metaphysical Realist observes a relation between perceptible things (mutual approach through movement, the entrance of an object into consciousness, etc.), there he posits a reality. However, the relation which he notices can only be expressed by means of thinking, but not perceived. The ideal relation is thereupon arbitrarily imagined as something perceptible. Thus, according to this theory, the real world is composed of the objects of perception which are in ceaseless flux, arising and disappearing, and of imperceptible forces by which the perceptible objects are produced, and which are permanent.

[ 25 ] Metaphysical Realism is a heterogeneous mixture of Naive Realism and Idealism. Its hypothetical forces are imperceptible entities endowed with the qualities proper to percepts. The Metaphysical Realist has made up his mind to acknowledge, in addition to the sphere for the existence of which he has an instrument of knowledge in sense-perception, the existence of another sphere for which this instrument fails, and which can be known only by means of thinking. But he cannot make up his mind at the same time to acknowledge that the mode of existence which thinking reveals, viz., the concept (or Idea), has equal rights with percepts. If we are to avoid the contradiction of imperceptible percepts, we must admit that, for us, the relations which thinking traces between percepts can have no other mode of existence than that of concepts. If one rejects the untenable part of Metaphysical Realism, there remains the concept of the world as the sum of percepts and their conceptual (ideal) relations. Metaphysical Realism, then, merges itself in a view of the world according to which the principle of perceptibility holds for percepts, and that of conceivability for the relations between the percepts. This view of the world has no room, in addition to the perceptual and conceptual worlds, for a third sphere, in which both principles, the so-called “real” principle and the “ideal” principle, are simultaneously valid.

[ 26 ] When the Metaphysical Realist asserts that, beside the ideal relation between the perceived object and the perceiving subject, there must exist a real relation between the “thing-in-itself” of the percept and the “thing-in-itself” of the perceptible subject (i.e., of the so-called individual spirit), he is basing his assertion on the false assumption of a real process, analogous to the processes in the sense-world, but imperceptible. Further, when the Metaphysical Realist asserts that we enter into a conscious ideal relation to our world of percepts, but that to the real world we can have only a dynamic (force) relation, he repeats the mistake we have already criticized. One can talk of a dynamic relation only within the world of percepts (in the sphere of the sense of touch), but not outside that world.

[ 27 ] Let us call the view which we have just characterized, and into which Metaphysical Realism merges when it discards its contradictory elements, Monism, because it combines one-sided Realism and Idealism into a higher unity.

[ 28 ] For Naive Realism, the real world is an aggregate of objects of perception; for Metaphysical Realism, reality belongs not only to percepts but also to imperceptible forces; Monism replaces forces by ideal connections which are supplied by thinking. Such connections are the Laws of Nature. A Law of Nature is nothing but the conceptual expression for the connection of certain percepts.

[ 29 ] Monism is never called upon to ask for any other principles of explanation for reality than percepts and concepts. It knows that in the whole range of the real there is no occasion for this question. In the perceptual world, as it lies before perception, it sees one-half of reality: in the union of this world with the world of concepts it finds full reality. The Metaphysical Realist may reply to the adherent of Monism that, for our organization, our knowledge may be complete in itself, that no part may be lacking; but we do not know how the world is mirrored in an Intelligence organized differently from our own. To this the Monist will reply: Maybe there are Intelligences other than human; if their percepts are different from ours, all that concerns me is what reaches me from them through perception and concept. Through my perceiving, i.e., through this specifically human mode of perceiving, I, as subject, am confronted with the object. The connection of things is thereby broken. The subject restores this connection by means of thinking. In doing so it re-inserts itself into the context of the world as a whole. As it is only through the subject that the whole appears rent in two at the place between our percept and concept, the reunion of those two factors gives us true knowledge. For beings with a different perceptual world (e.g., if they had twice our number of sense-organs) the nexus would appear broken in another place, and the reconstruction would accordingly have to take a form specific for such beings. The question concerning the limits of knowledge exists only for Naive and Metaphysical Realism, both of which see in the contents of the soul only an ideal representative of the real world. For, to these theories, whatever falls outside the subject is something absolute, a self-contained whole, and the subject's mental content is a picture thereof which is wholly external to this absolute. The completeness of knowledge depends on the greater or lesser degree of resemblance between the picture and the absolute object. A being with fewer senses than man will perceive less of the world, one with more senses will perceive more. The former's knowledge will, therefore, be less complete than the latter's.

[ 30 ] For Monism, the situation is different. The form in which the connection of the world appears to be rent asunder into subject and object depends on the organization of the perceiving being. The object is no absolute one but merely a relative one in reference to this particular subject. The bridging of the opposition, therefore, can again take place only in the quite specific way which is characteristic of the human subject. As soon as the I, which in perception is separated from the world, again reinserts itself into the world-nexus by thinking investigation, all further questioning ceases, having been but a consequence of the separation.

[ 31 ] A differently constituted being would have a differently-constituted knowledge. Our own knowledge, suffices to answer the questions put by our own nature.

[ 32 ] Metaphysical Realism must ask: How are our percepts given? What is it that affects the subject?

[ 33 ] Monism holds that percepts are determined through the subject. But, in thinking, the subject has, at the same time, the instrument for canceling this self-produced determination.

[ 34 ] The Metaphysical Realist is faced by a further difficulty when he seeks to explain the similarity of the world-pictures of different human individuals. He has to ask himself: How is it that my picture of the world, built up out of subjectively determined percepts and out of concepts, turns out to be like that which another individual is also building up out of these same two subjective factors? How, in any case, can I draw conclusions from my own subjective picture of the world on that of another human being? The Metaphysical Realist thinks he can infer the similarity of the subjective world-pictures of different human beings from their ability to get on with one another in practical life. From this similarity of world-pictures he then infers the likeness to one another of the “Individual Spirits” underlying the single human perceiving subjects, or the “I-in-itself” underlying the subjects.

[ 35 ] We have here an inference from a sum of effects to the character of the underlying causes. We believe we can, out of a sufficiently large number of instances, recognize the case sufficiently to know how the inferred causes will act in other instances. Such an inference is called an inductive inference. We shall be obliged to modify its results, if further observation yields some unexpected element, because the character of our conclusion is, after all, determined only by the particular shape of our actual observations. The Metaphysical Realist asserts that this knowledge of causes, though relative, is quite sufficient for practical life.

[ 36 ] Inductive inference is the methodical basis of modern Metaphysical Realism. At one time it was thought that out of concepts we could evolve something that is no longer a concept. It was thought that the metaphysical real Beings, which Metaphysical Realism after all requires, could be known by means of concepts. This kind of philosophizing is now out of date. Instead it is thought that from a sufficiently large number of perceptual facts one can infer the character of the thing-in-itself which underlies these facts. Formerly it was from concepts, now it is from percepts, that people seek to evolve the metaphysical. Since one has concepts before oneself in transparent clearness, it was thought that one might deduce from them the metaphysical with absolute certainty. Percepts are not given with the same transparent clearness. Each subsequent one is a little different from others of the same kind which preceded it. Actually, therefore, anything inferred from past percepts is somewhat modified by each subsequent percept. The character of the metaphysical thus obtained can, therefore, be only relatively true, for it is open to correction by further instances. The character of von Hartmann's Metaphysics is determined by this methodological principle. The motto on the title-page of his first important book is, “Speculative results gained by the inductive method of Natural Science.”

[ 37 ] The form which the Metaphysical Realist at the present day gives to his things-in-themselves is obtained by inductive inferences. Through considerations of the process of knowledge he is convinced of the existence of an objectively-real world-nexus, over and above the “subjective” world-nexus which we know by means of percepts and concepts. The nature of this reality he thinks he can determine by inductive inferences from his percepts.

Addition to the Revised Edition, 1918

[ 38 ] The unprejudiced study of experience, in perceiving and conceiving, such as we have attempted to describe it in the preceding chapter, is liable to be disturbed again and again by certain representations which spring from the soil of natural science. Thus, taking one's stand on science, one says that the eye perceives in the spectrum colours from red to violet. But beyond violet there lie forces within the compass of the spectrum to which corresponds, not a colour perceived by the eye, but a chemical effect. Similarly, beyond the activity of red, there are rays which have only heat effects. These and similar phenomena lead, on reflection, to the view that the range of man's perceptual world is defined by the range of his senses, and that he would have before himself a very different world if he had additional, or altogether different, senses. Those who like to indulge in far-roaming fancies for which the brilliant discoveries of recent scientific research in this direction provide a highly tempting occasion, may well be led to confess that nothing enters the field of man's observation except what-can affect his senses, as these have been determined by his organization. Man has no right to regard his percepts, limited as these are by his organization, as in any way a standard to which reality must conform. Every new sense would confront him with a different picture of reality. Within its proper limits, this is a wholly justified view. But if anyone lets himself be confused by this view in the unprejudiced study of the relation of percept and concept, as set forth in these chapters, he blocks the path for himself to a knowledge of man and the world which is rooted in reality. The experiencing of the essential nature of thinking, i.e., the active appropriation of the world of concepts, is something wholly different from the experiencing of a perceptible object through the senses. Whatever additional senses man might have, not one would give him reality, if his thinking did not permeate with concepts whatever he perceived by means of such a sense. Every sense, whatever its kind, provided only it is thus permeated, enables man to live amidst the real. The fancy-picture of other perceptual worlds, made possible by other senses, has nothing to do with the problem of how man stands in the midst of reality. We must clearly understand that every perceptual picture of the world owes its form to the organization of the perceiving being, but that only that perceptual picture which has been thoroughly permeated by a thinking investigation leads us into reality. Fanciful speculations concerning how different the world would appear to other than human senses, can give us no occasion to seek for knowledge of man's relation to the world; but only the recognition that every percept presents only a part of the reality it contains, and that, consequently, it leads us away from its own proper reality. This recognition is supplemented by the further one that thinking leads us into the part of reality which the percept conceals in itself. Another difficulty in the way of the unprejudiced study of the relation we have here described, between percept and concept as elaborated by thinking, may be met with, when in the field of physical experience the necessity arises of speaking, not of immediately perceptible elements, but of non-perceptible magnitudes, such as, e.g., lines of electric or magnetic force.

It may seem as if the elements of reality of which physicists speak, had no connection either with what is perceptible, or with the concepts which active thinking has elaborated. Yet such a view would rest on self-deception. The main point is that all the results of physical research, except illegitimate hypotheses which ought to be excluded, have been gained through perceiving and conceiving. Elements which are seemingly non-perceptible, are placed by the physicists' sound instinct for knowledge into the field in which percepts lie, and they are thought of in concepts which are commonly applied in this field. The magnitudes in a field of electric or magnetic force are reached, in their essence, by no other cognitive process that the one which connects percept and concept.—An increase or a modification of human senses would yield a different perceptual picture, an enrichment or a modification of human experience. But genuine knowledge could be gained also concerning this new experience only through the mutual co-operation of concept and percept. The deepening of knowledge depends on the powers of intuition which express themselves in thinking (see p. 70). This Intuition may, in the living experience which expresses itself in thinking, dive either into deeper or shallower levels of reality. An expansion of the perceptual picture may supply stimuli for, and thus indirectly promote, this diving of intuition. But this diving into the depth, through which we attain reality, ought never to be confused with the contrast between a wider and a narrower perceptual picture, which always contains only half of reality, as that is conditioned by the structure of the cognizing organization. He who does not lose himself in abstractions will understand how for a knowledge of human nature the fact is relevant, that physics must infer the existence, in the field of percepts, of elements for which no sense is tuned as for colour or sound. Human nature, taken concretely, is determined not only by what, in virtue of his organization, man faces as immediate percept, but also by all else which he excludes from this immediate percept. Just as life needs unconscious sleep alongside of conscious waking experience, so man's experience of himself needs over and above the range of his sense-perception another sphere—and a much bigger one—of non-perceptible elements belonging to the same field from which the percepts of the senses come. All this was laid down by implication in the original argument of this book. The author adds the present amplification of the argument, because he has found by experience that some readers have not read attentively enough.

It is to be remembered, too, that the Idea of percept, developed in this book, is not to be confused with the Idea of external sense-percept which is but a special instance of the other. The reader will gather from what has preceded, but even more from what will be expounded later, that everything is here taken as “percept,” which sensuously or spiritually approaches man, so long as it has not yet been grasped by the actively elaborated concept. No “senses,” as we ordinarily understand the term, are necessary in order to have percepts of a physical or spiritual kind. It may be urged that this extension of ordinary usage is illegitimate. But the extension is absolutely necessary, unless we are to be prevented by the current sense of a word from enlarging our knowledge of certain realms of facts. He who uses “percept” only as meaning “sense-percept,” will never arrive at a concept fit for the purposes of knowledge even regarding sense-percept. It is sometimes necessary to enlarge a concept in order that it may get its appropriate meaning within a narrower field. Again, it is at times necessary to add to the original content of a concept, in order that the original concept may be justified or, perhaps, readjusted. Thus we find it said here in this book (p. 80): “A representation is an individualized concept.” It has been objected that this is an unusual use of the word. But this use is necessary if we are to find out what a representation really is. How can we expect any progress in knowledge, if everyone who finds himself compelled to readjust concepts, is to be met by the objection: “This is an unusual use of the word”?

VII. Gibt es Grenzen des Erkennens?

[ 1 ] Wir haben festgestellt, daß die Elemente zur Erklärung der Wirklichkeit den beiden Sphären: dem Wahrnehmen und dem Denken zu entnehmen sind. Unsere Organisation bedingt es, wie wir gesehen haben, daß uns die volle, totale Wirklichkeit, einschließlich unseres eigenen Subjektes, zunächst als Zweiheit erscheint. Das Erkennen überwindet diese Zweiheit, indem es aus den beiden Elementen der Wirklichkeit: derWahrnehmung und dem durch das Denken erarbeiteten Begriff das ganze Ding zusammenfügt. Nennen wir die Weise, in der uns die Welt entgegentritt, bevor sie durch das Erkennen ihre rechte Gestalt gewonnen hat, die Welt der Erscheinung im Gegensatz zu der aus Wahrnehmung und Begriff einheitlich zusammengesetzten Wesenheit. Dann können wir sagen: Die Welt ist uns als Zweiheit (dualistisch) gegeben, und das Erkennen verarbeitet sie zur Einheit (monistisch). Eine Philosophie, welche von diesem Grundprinzip ausgeht, kann als monistische Philosophie oder Monismus bezeichnet werden. Ihr steht gegenüber die Zweiweltentheorie oder der Dualismus. Der letztere nimmt nicht etwa zwei bloß durch unsere Organisation auseinandergehaltene Seiten der einheitlichen Wirklichkeit an, sondern zwei voneinander absolut verschiedene Welten. Er sucht dann Erklärungsprinzipien für die eine Welt in der andern.

[ 2 ] Der Dualismus beruht auf einer falschen Auffassung des sen, was wir Erkenntnis nennen. Er trennt das gesamte Sein in zwei Gebiete, von denen jedes seine eigenen Gesetze hat, und läßt diese Gebiete einander äußerlich gegenüberstehen

[ 3 ] Einem solchen Dualismus entspringt die durch Kant in die Wissenschaft eingeführte und bis heute nicht wieder herausgebrachte Unterscheidung vonWahrnehmungsobjekt und «Ding an sich». Unseren Ausführungen gemäß liegt es in der Natur unserer geistigen Organisation, daß ein besonderes Ding, nur als Wahrnehmung gegeben sein kann. Das Denken überwindet dann die Besonderung, indem es jeder Wahrnehmung ihre gesetzmäßige Stelle im Weltganzen anweist. Solange die gesonderten Teile des Weltganzen als Wahrnehmungen bestimmt werden, folgen wir einfach in der Aussonderung einem Gesetze unserer Subjektivität. Betrachten wir aber die Summe aller Wahrnehmungen als den einen Teil und stellen diesem dann einen zweiten in den «Dingen an sich» gegenüber, so philosophieren wir ins Blaue hinein. Wir haben es dann mit einem bloßen Begriffsspiel zu tun. Wir konstruieren einen künstlichen Gegensatz, können aber für das zweite Glied desselben keinen Inhalt gewinnen, denn ein solcher kann für ein besonderes Ding nur aus der Wahrnehmung geschöpft werden.

[ 4 ] Jede Art des Seins, das außerhalb des Gebietes von Wahrnehmung und Begriff angenommen wird, ist in die Sphäre der unberechtigten Hypothesen zu verweisen. In diese Kategorie gehört das «Ding an sich». Es ist nur ganz natürlich, daß der dualistische Denker den Zusammenhang des hypothetisch angenommenen Weltprinzipes und des erfahrungsmäßig Gegebenen nicht finden kann. Für das hypothetische Weltprinzip läßt sich nur ein Inhalt gewinnen, wenn man ihn aus der Erfahrungswelt entlehnt und sich über diese Tatsache hinwegtäuscht. Sonst bleibt es ein inhaltsleerer Begriff, ein Unbegriff, der nur die Form des Begriffes hat. Der dualistische Denker behauptet dann gewöhnlich: der Inhalt dieses Begriffes sei unserer Erkenntnis unzugänglich; wir könnten nur wissen, daß ein solcher Inhalt vorhanden ist, nicht was vorhanden ist. In beiden Fällen ist die Überwindung des Dualismus unmöglich. Bringt man ein paar abstrakte Elemente der Erfahrungswelt in den Begriff des Dinges an sich hinein, dann bleibt es doch unmöglich, das reiche konkrete Leben der Erfahrung auf ein paar Eigenschaften zurückzuführen, die selbst nur aus dieser Wahrnehmung entnommen sind. Du Bois-Reymond denkt, daß die unwahrnehmbaren Atome der Materie durch ihre Lage und Bewegung Empfindung und Gefühl erzeugen, um dann zu dem Schlusse zu kommen: Wir können niemals zu einer befriedigenden Erklärung darüber kommen, wie Materie und Bewegung Empfindung und Gefühl erzeugen, denn «es ist eben durchaus und für immer unbegreiflich, daß es einer Anzahl von Kohlenstoff, Wasserstoff, Stickstoff, Sauerstoff, usw. Atomen nicht sollte gleichgültig sein, wie sie liegen und sich bewegen, wie sie lagen und sich bewegten, wie sie liegen und sich bewegen werden. Es ist in keiner Weise einzusehen, wie aus ihrem Zusammenwirken Bewußtsein entstehen könne». Diese Schlußfolgerung ist charakteristisch für die ganze Denkrichtung. Aus der reichen Welt der Wahrnehmungen wird abgesondert: Lage und Bewegung. Diese werden auf die erdachte Welt der Atome übertragen. Dann tritt die Verwunderung darüber ein, daß man aus diesem selbstgemachten und aus der Wahrnehmungswelt entlehnten Prinzip das konkrete Leben nicht herauswickeln kann.

[ 5 ] Daß der Dualist, der mit einem vollständig inhaltleeren Begriff vom An-sich arbeitet, zu keiner Welterklärung kommen kann, folgt schon aus der oben angegebenen Definition seines Prinzipes.

[ 6 ] In jedem Falle sieht sich der Dualist gezwungen, unserem Erkenntnisvermögen unübersteigliche Schranken zu setzen. Der Anhänger einer monistischen Weltanschauung weiß, daß alles, was er zur Erklärung einer ihm gegebenen Erscheinung der Welt braucht, im Bereiche der letztem liegen müsse. Was ihn hindert, dazu zu gelangen, können nur zufällige zeitliche oder räumliche Schranken oder Mängel seiner Organisation sein. Und zwar nicht der menschlichen Organisation im allgemeinen, sondern nur seiner besonderen individuellen.

[ 7 ] Es folgt aus dem Begriffe des Erkennens, wie wir ihn bestimmt haben, daß von Erkenntnisgrenzen nicht gesprochen werden kann. Das Erkennen ist keine allgemeine Weltangelegenheit, sondern ein Geschäft, das der Mensch mit sich selbst abzumachen hat. Die Dinge verlangen keine Erklärung. Sie existieren und wirken aufeinander nach den Gesetzen, die durch das Denken auffindbar sind. Sie existieren in unzertrennlicher Einheit mit diesen Gesetzen. Da tritt ihnen unsere Ichheit gegenüber und erfaßt von ihnen zunächst nur das, was wir als Wahrnehmung bezeichnet haben. Aber in dem Innern dieser Ichheit findet sich die Kraft, um auch den andern Teil der Wirklichkeit zu finden. Erst wenn die Ichheit die beiden Elemente der Wirklichkeit, die in der Welt unzertrennlich verbunden sind, auch für sich vereinigt hat, dann ist die Erkenntnisbefriedigung eingetreten: das Ich ist wieder bei der Wirklichkeit angelangt.

[ 8 ] Die Vorbedingungen zum Entstehen des Erkennens sind also durch und für das Ich. Das letztere gibt sich selbst die Fragen des Erkennens auf. Und zwar entnimmt es sie aus dem in sich vollständig klaren und durchsichtigen Elemente des Denkens. Stellen wir uns Fragen, die wir nicht beantworten können, so kann der Inhalt der Frage nicht in allen seinen Teilen klar und deutlich sein. Nicht die Welt stellt an uns die Fragen, sondern wir selbst stellen sie.

[ 9 ] Ich kann mir denken, daß mir jede Möglichkeit fehlt, eine Frage zu beantworten, die ich irgendwo aufgeschrieben finde, ohne daß ich die Sphäre kenne, aus der der Inhalt der Frage genommen ist.

[ 10 ] Bei unserer Erkenntnis handelt es sich um Fragen, die uns dadurch aufgegeben werden, daß einer durch Ort, Zeit und subjektive Organisation bedingten Wahrnehmungssphäre eine auf die Allheit der Welt weisende Begriffssphäre gegenübersteht. Meine Aufgabe besteht in dem Ausgleich dieser beiden mir wohlbekannten Sphären. Von einer Grenze der Erkenntnis kann da nicht gesprochen werden. Es kann zu irgendeiner Zeit dieses oder jenes unaufgeklärt bleiben, weil wir durch den Lebensschauplatz verhindert sind, die Dinge wahrzunehmen, die dabei im Spiele sind. Was aber heute nicht gefunden ist, kann es morgen werden. Die hierdurch bedingten Schranken sind nur vergängliche, die mit dem Fortschreiten von Wahrnehmung und Denken überwunden werden können.

[ 11 ] Der Dualismus begeht den Fehler, daß er den Gegensatz von Objekt und Subjekt, der nur innerhalb des Wahrnehmungsgebietes eine Bedeutung hat, auf rein erdachte Wesenheiten außerhalb desselben überträgt. Da aber die innerhalb des Wahrnehmungshorizontes gesonderten Dinge nur solange gesondert sind, als der Wahrnehmende sich des Denkens enthält, das alle Sonderung aufhebt und als eine bloß subjektiv bedingte erkennen läßt, so überträgt der Dualist Bestimmungen auf Wesenheiten hinter den Wahrnehmungen, die selbst für diese keine absolute, sondern nur eine relative Geltung haben. Er zerlegt dadurch die zwei für den Erkenntnisprozeß in Betracht kommenden Faktoren, Wahrnehmung und Begriff, in vier: 1. Das Objekt an sich; 2. die Wahrnehmung, die das Subjekt von dem Objekt hat; 3. das Subjekt; 4. den Begriff, der die Wahrnehmung auf das Objekt an sich bezieht. Die Beziehung zwischen dem Objekt und Subjekt ist eine reale; das Subjekt wird wirklich (dynamisch) durch das Objekt beeinflußt. Dieser reale Prozeß soll nicht in unser Bewußtsein fallen. Aber er soll im Subjekt eine Gegenwirkung auf die vom Objekt ausgehende Wirkung hervorrufen. Das Resultat dieser Gegenwirkung soll die Wahrnehmung sein. Diese falle erst ins Bewußtsein. Das Objekt habe eine objektive (vom Subjekt unabhängige), die Wahrnehmung eine subjektive Realität. Diese subjektive Realität beziehe das Subjekt auf das Objekt. Die letztere Beziehung sei eine ideelle. Der Dualismus spaltet somit den Erkenntnisprozeß in zwei Teile. Den einen, Erzeugung des Wahrnehmungsobjektes aus dem «Ding an sich», läßt er außerhalb, den andern, Verbindung der Wahrnehmung mit dem Begriff und Beziehung desselben auf das Objekt, innerhalb des Bewußtseins sich abspielen. Unter diesen Voraussetzungen ist es klar, daß der Dualist in seinen Begriffen nur subjektive Repräsentanten dessen zu gewinnen glaubt, was vor seinem Bewußtsein liegt. Der objektiv-realeVorgang im Subjekte, durch den die Wahrnehmung zustande kommt, und um so mehr die objektiven Beziehungen der «Dinge an sich» bleiben für einen solchen Dualisten direkt unerkennbar; seiner Meinung nach kann sich der Mensch nur begriffliche Repräsentanten für das objektiv Reale verschaffen. Das Einheitsband der Dinge, das diese unter sich und objektiv mit unserem Individualgeist (als «Ding an sich») verbindet, liegt jenseits des Bewußtseins in einem Wesen an sich, von dem wir in unserem Bewußtsein ebenfalls nur einen begrifflichen Repräsentanten haben könnten.

[ 12 ] Der Dualismus glaubt die ganze Welt zu einem abstrakten Begriffsschema zu verflüchtigen, wenn er nicht neben den begrifflichen Zusammenhängen der Gegenstände noch reale Zusammenhänge statuiert. Mit andern Worten: dem Dualisten erscheinen die durch das Denken auffindbaren Idealprinzipien zu luftig, und er sucht noch Realprinzipien, von denen sie gestützt werden können.

[ 13 ] Wir wollen uns diese Realprinzipien einmal näher anschauen. Der naive Mensch (naive Realist) betrachtet die Gegenstände der äußeren Erfahrung als Realitäten. Der Umstand, daß er diese Dinge mit seinen Händen greifen, mit seinen Augen sehen kann, gilt ihm als Zeugnis der Realität. «Nichts existiert, was man nicht wahrnehmen kann», ist geradezu als das erste Axiom des naiven Menschen anzusehen, das ebensogut in seiner Umkehrung anerkannt wird: «Alles, was wahrgenommen werden kann, existiert.» Der beste Beweis für diese Behauptung ist der Unsterblichkeits, und Geisterglaube des naiven Menschen. Er stellt sich die Seele als feine sinnliche Materie vor, die unter besonderen Bedingungen sogar für den gewöhnlichen Menschen sichtbar werden kann (naiver Gespensterglaube).

[ 14 ] Dieser seiner realen Welt gegenüber ist für den naiven Realisten alles andere, namentlich die Welt der Ideen, unreal, «bloß ideell». Was wir zu den Gegenständen hinzu-denken, das ist bloßer Gedanke über die Dinge. Der Gedanke fügt nichts Reales zu der Wahrnehmung hinzu.

[ 15 ] Aber nicht nur in bezug auf das Sein der Dinge hält der naive Mensch die Sinneswahrnehmung für das einzige Zeugnis der Realität, sondern auch in bezug auf das Geschehen. Ein Ding kann, nach seiner Ansicht, nur dann auf ein anderes wirken, wenn eine für die Sinneswahrnehmung vorhandene Kraft von dem einen ausgeht und das andere ergreift. Die ältere Physik glaubte, daß sehr feine Stoffe von den Körpern ausströmen und durch unsere Sinnesorgane in die Seele eindringen. Das wirkliche Sehen dieser Stoffe ist nur durch die Grobheit unserer Sinne im Verhältnis zu der Feinheit dieser Stoffe unmöglich. Prinzipiell gestand man diesen Stoffen aus demselben Grunde Realität zu, warum man es den Gegenständen der Sinnenwelt zugesteht, nämlich wegen ihrer Seinsform, die derjenigen der sinnenfälligen Realität analog gedacht wurde.

[ 16 ] Die in sich beruhende Wesenheit des ideell Erlebbaren gilt dem naiven Bewußtsein nicht in gleichem Sinne als real wie das sinnlich Erlebbare. Ein in der «bloßen Idee» gefaßter Gegenstand gilt so lange als bloße Schimäre, bis durch die Sinneswahrnehmung die Überzeugung von der Realität geliefert werden kann. Der naive Mensch verlangt, um es kurz zu sagen, zum ideellen Zeugnis seines Denkens noch das reale der Sinne. In diesem Bedürfnisse des naiven Menschen liegt der Grund zur Entstehung der primitiven Formen des Offenbarungsglaubens. Der Gott, der durch das Denken gegeben ist, bleibt dem naiven Bewußtsein immer nur ein «gedachter» Gott. Das naive Bewußtsein verlangt die Kundgebung durch Mittel, die der sinnlichen Wahrnehmung zugänglich sind. Der Gott muß leibhaftig erscheinen, und man will auf das Zeugnis des Denkens wenig geben, nur etwa darauf, daß die Göttlichkeit durch sinnenfällig konstatierbares Verwandeln von Wasser in Wein erwiesen wird.

[ 17 ] Auch das Erkennen selbst stellt sich der naive Mensch als einen den Sinnesprozessen analogen Vorgang vor. Die Dinge machen einen Eindruck in der Seele, oder sie senden Bilder aus, die durch die Sinne eindringen und so weiter.

[ 18 ] Dasjenige, was der naive Mensch mit den Sinnen wahrnehmen kann, das hält er für wirklich, und dasjenige, wovon er keine solche Wahrnehmung hat (Gott, Seele, das Erkennen usw.), das stellt er sich analog dem Wahrgenommenen vor.

[ 19 ] Will der naive Realismus eine Wissenschaft begründen, so kann er eine solche nur in einer genauen Beschreibung des Wahrnehmungsinhaltes sehen. Die Begriffe sind ihm nur Mittel zum Zweck. Sie sind da, um ideelle Gegenbilder für die Wahrnehmungen zu schaffen. Für die Dinge selbst bedeuten sie nichts. Als real gelten dem naiven Realisten nur die Tulpenindividuen, die gesehen werden, oder gesehen werden können; die eine Idee der Tulpe gilt ihm als Abstraktum, als das unreale Gedankenbild, das sich die Seele aus den allen Tulpen gemeinsamen Merkmalen zusammengefügt hat.

[ 20 ] Den naiven Realismus mit seinem Grundsatz von der Wirklichkeit alles Wahrgenommenen widerlegt die Erfahrung, welche lehrt, daß der Inhalt der Wahrnehmungen vergänglicher Natur ist. Die Tulpe, die ich sehe, ist heute wirklich; nach einem Jahr wird sie in Nichts verschwunden sein. Was sich behauptet hat, ist die Gattung Tulpe. Diese Gattung ist aber für den naiven Realismus «nur» eine Idee, keine Wirklichkeit. So sieht sich denn diese Weltanschauung in der Lage, ihre Wirklichkeiten kommen und verschwinden zu sehen, während sich das nach ihrer Meinung Unwirkliche dem Wirklichen gegenüber behauptet. Der naive Realismus muß also neben den Wahrnehmungen auch noch etwas Ideelles gelten lassen. Er muß Wesenheiten in sich aufnehmen, die er nicht mit den Sinnen wahrnehmen kann. Er findet sich dadurch mit sich selbst ab, daß er deren Daseinsform analog mit derjenigen der Sinnesobjekte denkt. Solche hypothetisch angenommenen Realitäten sind die unsichtbaren Kräfte, durch die die sinnlich wahrzunehmenden Dinge aufeinander wirken. Ein solches Ding ist die Vererbung, die über das Individuum hinaus fortwirkt, und die der Grund ist, daß sich aus dem Individuum ein neues entwickelt, das ihm ähnlich ist, wodurch sich die Gattung erhält. Ein solches Ding ist das den organischen Leib durchdringende Lebensprinzip, die Seele, für die man im naiven Bewußtsein stets einen nach Analogie mit Sinnesrealitäten gebildeten Begriff findet, und ist endlich das göttliche Wesen des naiven Menschen. Dieses göttliche Wesen wird in einer Weise wirksam gedacht, die ganz dem entspricht, was als Wirkungsart des Menschen selbst wahrgenommen werden kann: anthropomorphisch.

[ 21 ] Die moderne Physik führt die Sinnesempfindungen auf Vorgänge der kleinsten Teile der Körper und eines unendlich feinen Stoffes, des Äthers oder auf Ähnliches zurück. Was wir zum Beispiel als Wärme empfinden, ist innerhalb des Raumes, den der wärmeverursachende Körper einnimmt, Bewegung seiner Teile. Auch hier wird wieder ein Unwahrnehmbares in Analogie mit dem Wahrnehmbaren gedacht. Das sinnliche Analogon des Begriffs «Körper» ist in diesem Sinne etwa das Innere eines allseitig geschlossenen Raumes, in dem sich nach allen Richtungen elastische Kugeln bewegen, die einander stoßen, an die Wände an- und von ihnen abprallen und so weiter.

[ 22 ] Ohne solche Annahmen zerfiele dem naiven Realismus die Welt in ein unzusammenhängendes Aggregat von Wahrnehmungen ohne gegenseitige Beziehungen, das sich zu keiner Einheit zusammenschließt. Es ist aber klar, daß der naive Realismus nur durch eine Inkonsequenz zu dieser Annahme kommen kann. Wenn er seinem Grundsatz: nur das Wahrgenommene ist wirklich, treu bleiben will, dann darf er doch, wo er nichts wahrnimmt, kein Wirkliches annehmen. Die unwahrnehmbaren Kräfte, die von den wahrnehmbaren Dingen aus wirken, sind eigentlich unberechtigte Hypothesen vom Standpunkte des naiven Realismus. Und weil er keine anderen Realitäten kennt, so stattet er seine hypothetischen Kräfte mit Wahrnehmungsinhalt aus. Er wendet also eine Seinsform (das Wahrnehmungsdasein) auf ein Gebiet an, wo ihm das Mittel fehlt, das allein über diese Seinsform eine Aussage zu machen hat: das sinnliche Wahrnehmen.

[ 23 ] Diese in sich widerspruchsvolle Weltanschauung führt zum metaphysischen Realismus. Der konstruiert neben der wahrnehmbaren Realität noch eine unwahrnehmbare, die er der erstem analog denkt. Der metaphysische Realismus ist deshalb notwendig Dualismus.

[ 24 ] Wo der metaphysischeRealismus eine Beziehung zwischen wahrnehmbaren Dingen bemerkt (Annäherung durch Bewegung, Bewußtwerden eines Objektiven usw.), da setzt er eine Realität hin. Die Beziehung, die er bemerkt, kann er jedoch nur durch das Denken ausdrücken, nicht aber wahrnehmen. Die ideelle Beziehung wird willkürlich zu einem dem Wahrnehmbaren Ähnlichen gemacht. So ist für diese Denkrichtung die wirkliche Welt zusammengesetzt aus den Wahrnehmungsobjekten, die im ewigen Werden sind, kommen und verschwinden, und aus den unwahrnehmbaren Kräften, von denen die Wahrnehmungsobjekte hervorgebracht werden, und die das Bleibende sind.

[ 25 ] Der metaphysische Realismus ist eine widerspruchsvolle Mischung des naiven Realismus mit dem Idealismus. Seine hypothetischen Kräfte sind unwahrnehmbare Wesenheiten mitWahrnehmungsqualitäten.Er hat sich entschlossen, außer dem Weltgebiete, für dessen Daseinsform er in dem Wahrnehmen ein Erkenntnismittel hat, noch ein Gebiet gelten zu lassen, bei dem dieses Mittel versagt, und das nur durch das Denken zu ermitteln ist. Er kann sich aber nicht zu gleicher Zeit auch entschließen, die Form des Seins, die ihm das Denken vermittelt, den Begriff (die Idee), auch als gleichberechtigten Faktor neben der Wahrnehmung anzuerkennen. Will man den Widerspruch der unwahrnehmbaren Wahrnehmung vermeiden, so muß man zugestehen, daß es für die durch das Denken vermittelten Beziehungen zwischen den Wahrnehmungen für uns keine andere Existenzform als die des Begriffes gibt. Als die Summe von Wahrnehmungen und ihrer begrifflichen (ideellen) Bezüge stellt sich die Welt dar, wenn man aus dem metaphysischen Realismus den unberechtigten Bestandteil hinauswirft. So läuft der metaphysische Realismus in eine Weltanschauung ein, welche für die Wahrnehmung das Prinzip der Wahrnehmbarkeit, für die Beziehungen unter den Wahrnehmungen die Denkbarkeit fordert. Diese Weltanschauung kann kein drittes Weltgebiet neben der Wahrnehmungs, und Begriffswelt gelten lassen, für das beide Prinzipien, das sogenannte Realprinzip und das Idealprinzip, zugleich Geltung haben.

[ 26 ] Wenn der metaphysische Realismus behauptet, daß neben der ideellen Beziehung zwischen dem Wahrnehmungsobjekt und seinem Wahrnehmungssubjekt noch eine reale Beziehung zwischen dem «Ding an sich» der Wahrnehmung und dem «Ding an sich» des wahrnehmbaren Subjektes (des sogenannten Individualgeistes) bestehen muß, so beruht diese Behauptung auf der falschen Annahme eines den Prozessen der Sinnenwelt analogen, nicht wahrnehmbaren Seinsprozesses. Wenn ferner der metaphysische Realismus sagt: Mit meiner Wahrnehmungswelt komme ich in ein bewußt-ideelles Verhältnis; mit der wirklichen Welt kann ich aber nur in ein dynamisches (Kräfte) Verhältnis kommen, — so begeht er nicht weniger den schon gerügten Fehler. Von einem Kräfteverhältnis kann nur innerhalb der Wahrnehmungswelt (dem Gebiete des Tastsinnes), nicht aber außerhalb desselben die Rede sein.

[ 27 ] Wir wollen die oben charakterisierte Weltanschauung, in die der metaphysische Realismus zuletzt einmündet, wenn er seine widerspruchsvollen Elemente abstreift, Monismus nennen, weil sie den einseitigen Realismus mit dem Idealismus zu einer höheren Einheit vereinigt.

[ 28 ] Für den naiven Realismus ist die wirkliche Welt eine Summe von Wahrnehmungsobjekten; für den metaphysischen Realismus kommt außer den Wahrnehmungen auch noch den unwahrnehmbarenKräftenRealität zu;derMonismus setzt an die Stelle von Kräften die ideellen Zusammenhänge, die er durch sein Denken gewinnt. SolcheZusammenhänge aber sind die Naturgesetze. Ein Naturgesetz ist ja nichts anderes als der begriffliche Ausdruck für den Zusammenhang gewisser Wahrnehmungen.

[ 29 ] Der Monismus kommt gar nicht in die Lage, außer Wahrnehmung und Begriff nach anderen Erklärungsprinzipien der Wirklichkeit zu fragen. Er weiß, daß sich im ganzen Be reiche der Wirklichkeit kein Anlaß dazu findet. Er sieht in der Wahrnehmungswelt, wie sie unmittelbar dem Wahrnehmen vorliegt, ein halbes Wirkliches; in der Vereinigung derselben mit der Begriffswelt findet er die volle Wirklichkeit. Der metaphysische Realist kann dem Anhänger des Monismus einwenden: Es mag sein, daß für deine Organisation deine Erkenntnis in sich vollkommen ist, daß kein Glied fehlt; du weißt aber nicht, wie sich die Welt in einer Intelligenz abspiegelt, die anders organisiert ist als die deinige. Die Antwort des Monismus wird sein: Wenn es andere Intelligenzen gibt als die menschlichen, wenn ihre Wahrnehmungen eine andere Gestalt haben als die unsrigen, so hat für mich Bedeutung nur dasjenige, was von ihnen zu mir durch Wahrnehmen und Begriff gelangt. Ich bin durch mein Wahrnehmen, und zwar durch dieses spezifische menschliche Wahrnehmen als Subjekt dem Objekt gegenübergestellt. Der Zusammenhang der Dinge ist damit unterbrochen. Das Subjekt stellt durch das Denken diesen Zusammenhang wieder her.Damit hat es sich dem Weltganzen wieder eingefügt. Da nur durch unser Subjekt dieses Ganze an der Stelle zwischen unserer Wahrnehmung und unserem Begriff zerschnitten erscheint, so ist in der Vereinigung dieser beiden auch eine wahre Erkenntnis gegeben. Für Wesen mit einer andern Wahrnehmungswelt (zum Beispiel mit der doppelten Anzahl von Sinnesorganen) erschiene der Zusammenhang an einer andern Stelle unterbrochen, und die Wiederherstellung müßte demnach auch eine diesen Wesen spezifische Gestalt haben. Nur für den naiven und den metaphysischen Realismus, die beide in dem Inhalte der Seele nur eine ideelle Repräsentation der Welt sehen, besteht die Frage nach der Grenze des Erkennens. Für sie ist nämlich das außerhalb des Subjektes Befindliche ein Absolutes, ein in sich Beruhendes, und der Inhalt des Subjektes ein Bild desselben, das schlechthin außerhalb dieses Absoluten steht. Die Vollkommenheit der Erkenntnis beruht auf der größeren oder geringeren Ähnlichkeit des Bildes mit dem absoluten Objekte. Ein Wesen, bei dem die Zahl der Sinne kleiner ist, als beim Menschen, wird weniger, eines, bei dem sie größer ist, mehr von der Welt wahrnehmen. Das erstere wird demnach eine unvollkommenere Erkenntnis haben als das letztere.

[ 30 ] Für den Monismus liegt die Sache anders. Durch die Organisation des wahrnehmenden Wesens wird die Gestalt bestimmt, wo der Weltzusammenhang in Subjekt und Objekt auseinandergerissen erscheint. Das Objekt ist kein absolutes, sondern nur ein relatives, in bezug auf dieses bestimmte Subjekt. Die Überbrückung des Gegensatzes kann demnach auch nur wieder in der ganz spezifischen, gerade dem menschlichen Subjekt eigenen Weise geschehen. Sobald das Ich, das in dem Wahrnehmen von der Welt abgetrennt ist, in der denkenden Betrachtung wieder in denWeltzusammenhang sich einfügt, dann hört alles weitere Fragen, das nur eine Folge der Trennung war, auf.

[ 31 ] Ein anders geartetes Wesen hätte eine anders geartete Erkenntnis. Die unsrige ist ausreichend, um die durch unser eigenes Wesen aufgestellten Fragen zu beantworten.

[ 32 ] Der metaphysische Realismus muß fragen: Wodurch ist das als Wahrnehmung Gegebene gegeben; wodurch wird das Subjekt affiziert?

[ 33 ] Für den Monismus ist die Wahrnehmung durch das Subjekt bestimmt. Dieses hat aber in dem Denken zugleich das Mittel, die durch es selbst hervorgerufene Bestimmtheit wieder aufzuheben.

[ 34 ] Der metaphysische Realismus steht vor einer weiteren Schwierigkeit, wenn er die Ähnlichkeit der Weltbilder verschiedener menschlicher Individuen erklären will. Er muß sich fragen: Wie kommt es, daß das Weltbild, das ich aus meiner subjektiv bestimmten Wahrnehmung und meinen Begriffen aufbaue, gleichkommt dem, das ein anderes menschliches Individuum aus denselben beiden subjektiven Faktoren aufbaut? Wie kann ich überhaupt aus meinem subjektiven Weltbilde auf das eines andern Menschen schließen? Daraus, daß die Menschen sich miteinander praktisch abfinden, glaubt der metaphysische Realist die Ähnlichkeit ihrer subjektiven Weltbilder erschließen zu können. Aus der Ähnlichkeit dieser Weltbilder schließt er dann weiter auf die Gleichheit der den einzelnen menschlichen Wahrnehmungssubjekten zugrunde liegenden Individualgeister oder der den Subjekten zugrunde liegenden «Ich an sich».

[ 35 ] Dieser Schluß ist also ein solcher aus einer Summe von Wirkungen auf den Charakter der ihnen zugrunde liegenden Ursachen. Wir glauben aus einer hinreichend großen Anzahl von Fällen den Sachverhalt so zu erkennen, daß wir wissen, wie sich die erschlossenen Ursachen in andern Fällen verhalten werden. Einen solchen Schluß nennen wir einen Induktionsschluß. Wir werden uns gendtigt sehen, die Resultate desselben zu modifizieren, wenn in einer weitern Beobachtung etwas Unerwartetes sich ergibt, weil der Charakter des Resultates doch nur durch die individuelle Gestalt der geschehenen Beobachtungen bestimmt ist. Diese bedingte Erkenntnis der Ursachen reiche aber für das praktische Leben vollständig aus, behauptet der metaphysische Realist.

[ 36 ] Der Induktionsschluß ist die methodische Grundlage des modernen metaphysischen Realismus. Es gab eine Zeit, in der man aus Begriffen glaubte etwas herauswickeln zu können, was nicht mehr Begriff ist. Man glaubte aus den Begriffen die metaphysischen Realwesen, deren der metaphysische Realismus einmal bedarf, erkennen zu können. Diese Art des Philosophierens gehört heute zu den überwundenen Dingen. Dafür aber glaubt man, aus einer genügend großen Anzahl von Wahrnehmungstatsachen auf den Charakter des Dinges an sich schließen zu können, das diesen Tatsachen zugrunde liegt. Wie früher aus dem Begriffe, so meint man heute das Metaphysische aus den Wahrnehmungen heraus-wickeln zu können. Da man die Begriffe in durchsichtiger Klarheit vor sich hat, so glaubte man aus ihnen auch das Metaphysische mit absoluter Sicherheit ableiten zu können. Die Wahrnehmungen liegen nicht mit gleich durchsichtiger Klarheit vor. Jede folgende stellt sich wieder etwas anders dar, als die gleichartigen vorhergehenden. Im Grunde wird daher das aus den vorhergehenden Erschlossene durch jede folgende etwas modifiziert. Die Gestalt, die man auf diese Weise für das Metaphysische gewinnt, ist also nur eine relativ richtige zu nennen; sie unterliegt der Korrektur durch künftige Fälle. Einen durch diesen methodischen Grundsatz bestimmten Charakter trägt die Metaphysik Eduard von Hartmanns, der als Motto auf das Titelblatt seines ersten Hauptwerkes gesetzt hat: «Spekulative Resultate nach induktiv naturwissenschaftlicher Methode. »

[ 37 ] Die Gestalt, die der metaphysische Realist gegenwärtig seinen Dingen an sich gibt, ist eine durch Induktionsschlüsse gewonnene. Von dem Vorhandensein eines objektiv-realen Zusammenhanges der Welt neben dem «subjektiven» durch Wahrnehmung und Begriff erkennbaren, ist er durch Erwägungen über den Erkenntnisprozeß überzeugt. Wie diese objektive Realität beschaffen ist, das glaubt er durch Induktionsschlüsse aus seinen Wahrnehmungen heraus bestimmen zu können.

Zusatz zur Neuausgabe (1918)

[ 38 ] Für die unbefangene Beobachtung des Erlebens in Wahrnehmung und Begriff, wie sie in den vorangehenden Ausführungen zu schildern versucht worden ist, werden gewisse Vorstellungen immer wieder störend sein, die auf dem Boden der Naturbetrachtung entstehen. Man sagt sich, auf diesem Boden stehend, durch das Auge werden im Lichtspektrum Farben wahrgenommen vom Rot bis zum Violett. Aber über das Violett hinaus liegen im Strahlungsraum des Spektrums Kräfte, welchen keine Farbwahrnehmung des Auges, wohl aber eine chemische Wirkung entspricht; ebenso liegen über die Grenze der Rotwirksamkeit hinaus Strahlungen, die nur Wärmewirkungen haben. Man kommt durch Überlegungen, die auf solche und ähnliche Erscheinungen gerichtet sind, zu der Ansicht: der Umfang.der menschlichen Wahrnehmungswelt ist durch den Umfang der Sinne des Menschen bestimmt, und dieser würde eine ganz andere Welt vor sich haben, wenn er zu den seinigen noch andere, oder wenn er überhaupt andere Sinne hätte. Wer sich ergehen mag in den ausschweifenden Phantasien, zu denen, nach dieser Richtung hin, namentlich die glänzenden Entdeckungen der neueren Naturforschung eine recht verführerische Veranlassung bieten, der kann wohl zu dem Bekenntnisse kommen: In des Menschen Beobachtungsfeld fällt doch nur dasjenige herein, was auf die aus seiner Organisation heraus gestalteten Sinne zu wirken vermag. Er hat kein Recht, dieses von ihm durch seine Organisation begrenzte Wahrgenommene als irgendwie maßgeblich für die Wirklichkeit anzusehen. Jeder neue Sinn müßte ihn vor ein anderes Bild der Wirklichkeit stellen. — Dies alles ist, in den entsprechenden Grenzen gedacht, eine durchaus berechtigte Meinung. Wenn aber jemand sich durch diese Meinung in der unbefangenen Beobachtung des in diesen Ausführungen geltend gemachten Verhältnisses von Wahrnehmung und Begriff beirren läßt, so verbaut er sich den Weg zu einer in der Wirklichkeit wurzelnden Welt, und Menschenerkenntnis. Das Erleben der Wesenheit des Denkens, also die tätige Erarbeitung der Begriffswelt ist etwas durchaus anderes als das Erleben eines Wahrnehmbaren durch die Sinne. Welche Sinne immer der Mensch noch haben könnte: keiner gäbe ihm eine Wirklichkeit, wenn er nicht das durch ihn vermittelte Wahrgenommene denkend mit Begriffen durchsetzte; und jeder wie immer geartete Sinn gibt, so durchsetzt, dem Menschen die Möglichkeit, in der Wirklichkeit drinnen zu leben. Mit der Frage: wie der Mensch in der wirklichen Welt steht, hat die Phantasie von dem möglichen ganz anderen Wahrnehmungsbild bei anderen Sinnen nichts zu tun. Man muß eben einsehen, daß jedes Wahrnehmungsbild seine Gestalt erhält von der Organisation des wahrnehmenden Wesens, daß aber das von der erlebten denkenden Betrachtung durchsetzte Wahrnehmungsbild den Menschen in dieWirklichkeit führt. Nicht die phantastische Ausmalung, wie anders eine Welt für andere als die menschlichen Sinne aussehen müßte, kann den Menschen veranlassen, Erkenntnis zu suchen über sein Verhältnis zur Welt, sondern die Einsicht, daß jede Wahrnehmung nur einen Teil der in ihr steckenden Wirklichkeit gibt, daß sie also von ihrer eigenen Wirklichkeit hinwegführt. Dieser Einsicht tritt dann die andere zur Seite, daß das Denken in den durch die Wahrnehmung an ihr selbst verborgenen Teil der Wirklichkeit hineinführt. Störend für die unbefangene Beobachtung des hier dargestellten Verhältnisses zwischen Wahrnehmung und denkend erarbeitetem Begriff kann auch werden, wenn im Gebiete der physikalischen Erfahrung sich die Nötigung ergibt, gar nicht von unmittelbar anschaulich-wahrnehmbaren Elementen, sondern von unanschaulichen Größen wie elektrischen oder magnetischen Kraftlinien und so weiter zu sprechen. Es kann scheinen, als ob die Wirklichkeitselemente, von denen die Physik spricht, weder mit dem Wahrnehmbaren, noch mit dem im tätigen Denken erarbeiteten Begriff etwas zu tun hätten. Doch beruhte eine solche Meinung auf einer Selbsttäuschung. Zunächst kommt es darauf an, daß alles in der Physik Erarbeitete, insofern es nicht unberechtigte Hypothesen darstellt, die ausgeschlossen bleiben sollten, durch Wahrnehmung und Begriff gewonnen ist. Was scheinbar unanschaulicher Inhalt ist, das wird aus einem richtigen Erkenntnisinstinkt des Physikers heraus durchaus in das Feld versetzt, auf dem die Wahrnehmungen liegen, und es wird in Begriffen gedacht, mit denen man sich auf diesem Felde betätigt. Die Kraftstärken im elektrischen und magnetischen Felde und so weiter werden, dem Wesen nach, nicht durch einen andern Erkenntnisvorgang gewonnen als durch denjenigen, der sich zwischen Wahrnehmung und Begriff abspielt. — Eine Vermehrung oder Andersgestaltung der menschlichen Sinne würde ein anderes Wahrnehmungsbild ergeben, eine Bereicherung oder Andersgestaltung der menschlichen Erfahrung; aber eine wirkliche Erkenntnis müßte auch dieser Erfahrung gegenüber durch die Wechselwirkung von Begriff und Wahrnehmung gewonnen werden. Die Vertiefung der Erkenntnis hängt von den im Denken sich auslebenden Kräften der Intuition (vergleiche Seite 95) ab. Diese Intuition kann in demjenigen Erleben, das im Denken sich ausgestaltet, in tiefere oder weniger tiefe Untergründe der Wirklichkeit tauchen. Durch die Erweiterung des Wahrnehmungsbildes kann dieses Untertauchen Anregungen empfangen und auf diese Art mittelbar gefördert werden. Allein niemals sollte das Tauchen in die Tiefe, als das Erreichen der Wirklichkeit, verwechselt werden mit dem Gegenüberstehen von weiterem oder engerem Wahrnehmungsbild, in dem stets nur eine halbe Wirklichkeit, wie sie von der erkennenden Organisation bedingt wird, vorliegt. Wer nicht in Abstraktionen sich verliert, der wird einsehen, wie auch die Tatsache für die Erkenntnis des Menschenwesens in Betracht kommt, daß für die Physik imWahrnehmungsfelde Elemente erschlossen werden müssen, für welche nicht ein Sinn wie für Farbe oder Ton unmittelbar abgestimmt ist. Das konkrete Wesen des Menschen ist nicht nur durch dasjenige bestimmt, was er durch seine Organisation sich als unmittelbare Wahrnehmung gegenüberstellt, sondern auch dadurch, daß er anderes von dieser unmittelbaren Wahrnehmung ausschließt. Wie dem Leben neben dem bewußten Wachzustande der unbewußte Schlafzustand notwendig ist, so ist dem Sich-Erleben des Menschen neben dem Umkreis seiner Sinneswahrnehmung notwendig ein - viel größerer sogar - Umkreis von nicht sinnlich wahrnehmbaren Elementen in dem Felde, aus dem die Sinneswahrnehmungen stammen. Dies alles ist mittelbar schon ausgesprochen in der ursprünglichen Darstellung dieser Schrift. Deren Verfasser fügt hier diese Erweiterung des Inhaltes an, weil er die Erfahrung gemacht hat, daß mancher Leser nicht genau genug gelesen hat. - Bedacht sollte auch werden, daß die Idee von der Wahrnehmung, wie sie in dieser Schrift entwickelt wird, nicht verwechselt werden darf mit derjenigen von äußerer Sinnes-wahrnehmung, die nur ein Spezialfall von ihr ist. Man wird aus dem schon Vorangehenden, aber noch mehr aus dem später Ausgeführten ersehen, daß hier alles sinnlich und geistig an den Menschen Herantretende als Wahrnehmung aufgefaßt wird, bevor es von dem tätig erarbeiteten Begriff erfaßt ist. Um Wahrnehmungen seelischer oder geistiger Art zu haben, sind nicht Sinne von gewöhnlich gemeinter Art nötig. Man könnte sagen, solche Erweiterung des üblichen Sprachgebrauches sei unstatthaft. Allein sie ist unbedingt notwendig, wenn man sich nicht auf gewissen Gebieten eben durch den Sprachgebrauch in der Erkenntniserweiterung fesseln lassen will. Wer von Wahrnehmung nur im Sinne von sinnlicher Wahrnehmung spricht, der kommt auch über diese sinnliche Wahrnehmung nicht zu einem für die Erkenntnis brauchbaren Begriff. Man muß manchmal einen Begriff erweitern, damit er auf einem engeren Gebiete seinen ihm angemessenen Sinn erhält. Man muß auch zuweilen zu dem, was in einem Begriffe zunächst gedacht wird, anderes hinzufügen, damit das so Gedachte seine Rechtfertigung oder auch Zurechtrückung findet. So findet man auf Seite 107 dieses Buches gesagt: «Die Vorstellung ist also ein individualisierter Begriff.» Demgegenüber wurde mir eingewendet, das sei ein ungewöhnlicher Wortgebrauch. Aber dieser Wortgebrauch ist notwendig, wenn man dahinterkommen will, was Vorstellung eigentlich ist. Was sollte aus dem Fortgang der Erkenntnis werden, wenn man jedem, der in die Notwendigkeit versetzt ist, Begriffe zurechtzurücken, den Einwand machte: «Das ist ein ungewöhnlicher Wortgebrauch.»

VII: Are there limits to cognition?

[ 1 ] We have established that the elements for explaining reality are to be taken from the two spheres: perception and thought. As we have seen, our organization means that the full, total reality, including our own subject, initially appears to us as a duality. Cognition overcomes this duality by assembling the whole thing from the two elements of reality: perception and the concept developed through thinking. Let us call the way in which the world confronts us before it has gained its proper form through cognition the world of appearance in contrast to the entity composed of perception and concept. Then we can say: The world is given to us as a duality (dualistic), and cognition processes it into unity (monistic). A philosophy based on this fundamental principle can be described as monistic philosophy or monism. It is contrasted with the two-world theory or dualism. The latter does not assume two sides of the unified reality that are merely kept apart by our organization, but two absolutely different worlds. It then seeks explanatory principles for one world in the other.

[ 2 ] Dualism is based on a false conception of what we call cognition. It separates the whole of existence into two domains, each of which has its own laws, and leaves these domains externally opposed to each other

[ 3 ] The distinction between the object of perception and the "thing in itself", which was introduced into science by Kant and has not been removed to this day, arises from such dualism. According to our explanations, it is in the nature of our mental organization that a particular thing can only be given as perception. Thinking then overcomes particularization by assigning each perception its lawful place in the world as a whole. As long as the separate parts of the whole of the world are determined as perceptions, we are simply following a law of our subjectivity in the separation. But if we regard the sum of all perceptions as one part and then contrast this with a second part in the "things in themselves", we are philosophizing into the blue. We are then dealing with a mere conceptual game. We construct an artificial contrast, but cannot gain any content for the second part of it, because such a content can only be drawn from perception for a particular thing.

[ 4 ] Any kind of being that is assumed to exist outside the realm of perception and concept is to be relegated to the sphere of unjustified hypotheses. The "thing in itself" belongs to this category. It is only natural that the dualistic thinker cannot find the connection between the hypothetically assumed world principle and the experientially given. A content can only be gained for the hypothetical world principle if it is borrowed from the world of experience and this fact is ignored. Otherwise it remains an empty concept, a non-concept that only has the form of a concept. The dualistic thinker then usually claims that the content of this concept is inaccessible to our cognition; we can only know that such a content exists, not what exists. In both cases, overcoming dualism is impossible. If one brings a few abstract elements of the world of experience into the concept of the thing in itself, then it remains impossible to attribute the rich concrete life of experience to a few properties that are themselves only taken from this perception. Du Bois-Reymond thinks that the imperceptible atoms of matter generate sensation and feeling through their position and movement, and then comes to the conclusion: We can never arrive at a satisfactory explanation of how matter and motion produce sensation and feeling, for "it is quite and for ever incomprehensible that a number of carbon, hydrogen, nitrogen, oxygen, etc., atoms should not be indifferent to each other. atoms should not be indifferent to how they lie and move, how they lay and moved, how they will lie and move. It is in no way comprehensible how consciousness could arise from their interaction". This conclusion is characteristic of the entire school of thought. From the rich world of perceptions is separated: Position and movement. These are transferred to the imaginary world of atoms. Then comes the astonishment that concrete life cannot be developed out of this self-made principle borrowed from the world of perception.

[ 5 ] It follows from the definition of his principle given above that the dualist, who works with a completely empty concept of the "in itself", cannot arrive at any explanation of the world.

[ 6 ] In any case, the dualist is forced to set insurmountable limits to our cognitive capacity. The adherent of a monistic worldview knows that everything he needs to explain a given phenomenon of the world must lie in the realm of the ultimate. What prevents him from arriving at this can only be accidental temporal or spatial barriers or deficiencies in his organization. And not the human organization in general, but only its particular individual organization.

[ 7 ] It follows from the concept of cognition, as we have defined it, that we cannot speak of limits to cognition. Cognition is not a general world affair, but a business that man has to settle with himself. Things do not demand an explanation. They exist and interact according to the laws that can be discovered through thinking. They exist in inseparable unity with these laws. Our ego confronts them and initially only grasps what we have described as perception. But the power to find the other part of reality is found within this ego. Only when the ego has united the two elements of reality, which are inseparably connected in the world, has the satisfaction of cognition occurred: the ego has arrived at reality again.

[ 8 ] The preconditions for the emergence of cognition are therefore by and for the ego. The latter poses the questions of cognition to itself. It takes them from the element of thinking, which is completely clear and transparent in itself. If we ask ourselves questions that we cannot answer, the content of the question cannot be clear and distinct in all its parts. It is not the world that asks us questions, but we ask them ourselves.

[ 9 ] I can imagine that I lack any possibility of answering a question that I find written down somewhere without knowing the sphere from which the content of the question is taken.

[ 10 ] Our cognition involves questions that are posed to us by the fact that a sphere of perception conditioned by place, time and subjective organization is confronted by a sphere of concepts pointing to the universality of the world. My task consists in balancing these two spheres, which are well known to me. There can be no talk of a limit to cognition. This or that can remain unexplained at any given time because we are prevented by the scene of life from perceiving the things that are involved. But what is not found today may be found tomorrow. The barriers caused by this are only temporary and can be overcome with the progression of perception and thought.

[ 11 ] Dualism makes the mistake of transferring the opposition of object and subject, which only has meaning within the realm of perception, to purely imagined entities outside of it. But since the things separated within the perceptual horizon are only separate as long as the perceiver abstains from thinking, which abolishes all separation and allows it to be recognized as merely subjectively conditioned, the dualist transfers determinations to entities behind the perceptions, which themselves have no absolute, but only a relative validity for them. He thus breaks down the two factors relevant to the process of cognition, perception and concept, into four: 1. the object in itself; 2. the perception that the subject has of the object; 3. the subject; 4. the concept that relates the perception to the object in itself. The relationship between the object and the subject is a real one; the subject is really (dynamically) influenced by the object. This real process should not fall into our consciousness. But it is supposed to produce a counter-effect in the subject to the effect emanating from the object. The result of this counter-effect should be perception. This only falls into consciousness. The object has an objective reality (independent of the subject), the perception a subjective reality. This subjective reality relates the subject to the object. The latter relationship is an ideal one. Dualism thus splits the process of cognition into two parts. One part, the creation of the object of perception from the "thing in itself", takes place outside, the other, the connection of perception with the concept and its relation to the object, within consciousness. Under these conditions, it is clear that the dualist believes to gain in his concepts only subjective representations of what lies before his consciousness. The objectively real process in the subject, through which perception comes about, and all the more the objective relationships of the "things in themselves" remain directly unrecognizable for such a dualist; in his opinion, man can only obtain conceptual representations for the objectively real. The unifying bond of things, which connects them among themselves and objectively with our individual spirit (as a "thing in itself"), lies beyond consciousness in a being in itself, of which we could also only have a conceptual representative in our consciousness.

[ 12 ] Dualism believes that the whole world evaporates into an abstract conceptual scheme if it does not establish real connections alongside the conceptual connections of the objects. In other words: for the dualist, the ideal principles that can be found through thinking appear too airy, and he still seeks real principles that can support them.

[ 13 ] Let us take a closer look at these real principles. The naive person (naive realist) regards the objects of external experience as realities. The fact that he can grasp these things with his hands and see them with his eyes is regarded by him as evidence of reality. "Nothing exists that cannot be perceived" is virtually the first axiom of the naive person, which is just as well recognized in its inversion: "Everything that can be perceived exists." The best proof of this assertion is the naive person's belief in immortality and spirits. They imagine the soul as subtle sensual matter that can even become visible to ordinary people under special conditions (naive belief in ghosts).

[ 14 ] For the naive realist, everything else, namely the world of ideas, is unreal, "merely ideal" in comparison to this real world. What we think in addition to the objects is merely thought about the things. Thought adds nothing real to perception.

[ 15 ] But it is not only with regard to the existence of things that the naive person considers sense perception to be the only testimony to reality, but also with regard to events. In his view, one thing can only have an effect on another if a force available for sensory perception emanates from the one and grips the other. The older physics believed that very fine substances emanate from the bodies and penetrate the soul through our sensory organs. The real seeing of these substances is only impossible because of the coarseness of our senses in relation to the fineness of these substances. In principle, these substances were conceded reality for the same reason that objects of the sensory world are conceded reality, namely because of their form of being, which was thought to be analogous to that of sensory reality.

[ 16 ] The intrinsic essence of the ideal experience is not regarded by the naive consciousness as real in the same sense as the sensory experience. An object grasped in the "mere idea" is regarded as a mere chimera until the conviction of reality can be delivered through sensory perception. To put it briefly, the naive person demands the real testimony of the senses in addition to the ideal testimony of his thinking. In this need of naive man lies the reason for the emergence of primitive forms of belief in revelation. The God who is given through thinking always remains only a "thought" God to the naive consciousness. The naive consciousness demands manifestation through means that are accessible to sensory perception. The God must appear in the flesh, and one wants to place little value on the testimony of thought, only, for example, on the fact that divinity is proven through the sensually ascertainable transformation of water into wine.

[ 17 ] The naive person also imagines cognition itself as a process analogous to sensory processes. Things make an impression in the soul, or they send out images that penetrate through the senses and so on.

[ 18 ] That which the naive person can perceive with the senses, he considers to be real, and that of which he has no such perception (God, soul, cognition, etc.), he imagines to be analogous to what he perceives.

[ 19 ] If naive realism wants to establish a science, it can only see such a science in an exact description of the content of perception. The concepts are only a means to an end. They are there to create ideal counter-images for the perceptions. They mean nothing for the things themselves. For the naive realist, only the tulip individuals that are seen or can be seen are considered real; the one idea of the tulip is considered an abstraction, an unreal mental image that the soul has assembled from the characteristics common to all tulips.

[ 20 ] Naïve realism with its principle of the reality of everything perceived is refuted by experience, which teaches that the content of perceptions is of a transitory nature. The tulip that I see is real today; after a year it will have disappeared into nothingness. What has survived is the genus tulip. For naive realism, however, this genus is "only" an idea, not a reality. Thus, this worldview sees itself in a position to see its realities come and disappear, while what it considers to be unreal asserts itself against the real. Naive realism must therefore accept something ideal in addition to perceptions. It must take into itself entities that it cannot perceive with the senses. It comes to terms with itself by thinking their form of existence analogous to that of the sense objects. Such hypothetically assumed realities are the invisible forces through which the sensually perceptible things interact. Such a thing is heredity, which continues beyond the individual, and which is the reason why a new one develops from the individual, which is similar to it, whereby the species is preserved. Such a thing is the life principle that permeates the organic body, the soul, for which one always finds a concept in naive consciousness formed by analogy with sense realities, and is finally the divine essence of naive man. This divine essence is thought to be effective in a way that corresponds entirely to what can be perceived as the mode of action of man himself: anthropomorphic.

[ 21 ] Modern physics attributes sensory perceptions to processes of the smallest parts of bodies and an infinitely fine substance, the ether or something similar. What we perceive as heat, for example, is the movement of its parts within the space occupied by the body that causes the heat. Here again, the imperceptible is conceived in analogy with the perceptible. In this sense, the sensory analog of the term "body" is, for example, the interior of a room closed on all sides, in which elastic spheres move in all directions, colliding with each other, bouncing against and off the walls and so on.

[ 22 ] Without such assumptions, naïve realism would see the world as a disjointed aggregate of perceptions without mutual relationships that does not coalesce into a unity. It is clear, however, that naive realism can only arrive at this assumption through an inconsistency. If it wants to remain true to its principle that only what is perceived is real, then it cannot assume anything real where it perceives nothing. The imperceptible forces that act from the perceptible things are actually unjustified hypotheses from the standpoint of naive realism. And because it knows of no other realities, it endows its hypothetical forces with perceptual content. He thus applies a form of being (perceptual existence) to an area where he lacks the means that alone can make a statement about this form of being: sensory perception.

[ 23 ] This inherently contradictory worldview leads to metaphysical realism. In addition to the perceptible reality, it constructs an imperceptible one, which it thinks is analogous to the first. Metaphysical realism is therefore necessarily dualism.

[ 24 ] Where metaphysical realism notices a relationship between perceptible things (approach through movement, becoming aware of an objective, etc.), it posits a reality. However, the relationship he notices can only be expressed by thinking, not perceived. The ideal relationship is arbitrarily made into something similar to the perceptible. Thus, for this school of thought, the real world is composed of the objects of perception, which are in eternal becoming, coming and disappearing, and of the imperceptible forces by which the objects of perception are produced and which are the permanent things.

[ 25 ] Metaphysical realism is a contradictory mixture of naive realism and idealism. Its hypothetical powers are imperceptible entities with perceptual qualities, and it has decided to admit, in addition to the realm of the world for whose form of existence it has a means of knowledge in perception, a realm in which this means fails and which can only be determined by thinking. At the same time, however, he cannot also decide to recognize the form of being that thinking conveys to him, the concept (the idea), as an equally valid factor alongside perception. If we want to avoid the contradiction of imperceptible perception, we must concede that for us there is no other form of existence for the relationships between perceptions mediated by thinking than that of the concept. The world presents itself as the sum of perceptions and their conceptual (ideal) references if we throw out the unjustified component of metaphysical realism. Thus metaphysical realism leads to a worldview that demands the principle of perceptibility for perception and conceivability for the relationships between perceptions. This worldview cannot accept a third realm alongside the perceptual and conceptual world, for which both principles, the so-called real principle and the ideal principle, are valid at the same time.

[ 26 ] If metaphysical realism asserts that, in addition to the ideal relationship between the object of perception and its subject of perception, there must also be a real relationship between the "thing in itself" of perception and the "thing in itself" of the perceptible subject (the so-called individual spirit), then this assertion is based on the false assumption of a non-perceptible process of being analogous to the processes of the sense world. Furthermore, when metaphysical realism says: With my perceptual world I come into a conscious-ideal relationship; with the real world, however, I can only come into a dynamic (force) relationship, - it commits no less the error already criticized. We can only speak of a relation of forces within the world of perception (the realm of the sense of touch), but not outside it.

[ 27 ] We want to call the world view characterized above, into which metaphysical realism ultimately leads when it sheds its contradictory elements, monism, because it unites one-sided realism with idealism into a higher unity.

[ 28 ] For naïve realism, the real world is a sum of perceptual objects; for metaphysical realism, in addition to perceptions, the imperceptible forces also have reality; monism replaces forces with ideal connections, which it gains through its thinking. Such connections, however, are the laws of nature. A law of nature is nothing other than the conceptual expression for the connection between certain perceptions.

[ 29 ] Monism is not in a position to ask for other principles of explanation of reality apart from perception and concept. It knows that there is no reason to do so in the whole realm of reality. He sees in the perceptual world, as it is immediately available to perception, a half-reality; in the union of this with the conceptual world he finds the full reality. The metaphysical realist can object to the supporter of monism: It may be that for your organization your cognition is perfect in itself, that no link is missing; but you do not know how the world is reflected in an intelligence that is organized differently from yours. The answer of monism will be: If there are intelligences other than human intelligences, if their perceptions have a different form than ours, then only that which comes to me from them through perception and conception has meaning for me. Through my perception, and indeed through this specific human perception, I am confronted with the object as subject. The connection between things is thus interrupted. The subject re-establishes this connection through thinking and has thus reintegrated itself into the world as a whole. Since it is only through our subject that this whole appears to be severed at the point between our perception and our concept, true knowledge is also given in the unification of these two. For beings with a different perceptual world (for example, with twice the number of sense organs), the connection would appear to be interrupted at a different point, and the restoration would therefore also have to have a form specific to these beings. Only for naive and metaphysical realism, both of which see in the content of the soul only an ideal representation of the world, does the question of the limit of cognition exist. For them, that which is outside the subject is an absolute, something that rests in itself, and the content of the subject is an image of it that stands absolutely outside this absolute. The perfection of cognition is based on the greater or lesser similarity of the image to the absolute object. A being in which the number of senses is smaller than in man will perceive less of the world, one in which it is greater will perceive more. The former will therefore have a more imperfect cognition than the latter.

[ 30 ] For monism, the situation is different. The form is determined by the organization of the perceiving being, where the world context appears torn apart into subject and object. The object is not an absolute, but only a relative one in relation to this particular subject. The bridging of the opposition can therefore only happen again in the very specific way that is peculiar to the human subject. As soon as the ego, which is separated from the world in perception, is reintegrated into the world context in thinking observation, then all further questioning, which was only a consequence of the separation, ceases.

[ 31 ] A different kind of being would have a different kind of cognition. Ours is sufficient to answer the questions posed by our own being.

[ 32 ] Metaphysical realism must ask: By what is that which is given as perception given; by what is the subject affected?

[ 33 ] For monism, perception is determined by the subject. At the same time, however, the subject has in thinking the means to abolish the determination caused by itself.

[ 34 ] Metaphysical realism faces a further difficulty if it wants to explain the similarity of the world views of different human individuals. It must ask itself: How is it that the world view that I construct from my subjectively determined perception and my concepts is the same as that which another human individual constructs from the same two subjective factors? How can I even draw conclusions from my subjective world view to that of another person? The metaphysical realist believes that he can deduce the similarity of their subjective world views from the fact that people practically come to terms with each other. From the similarity of these world views, he then further infers the sameness of the individual spirits underlying the individual human subjects of perception or the "I in itself" underlying the subjects.

[ 35 ] This conclusion is thus one from a sum of effects to the character of the underlying causes. We believe that we can recognize the facts from a sufficiently large number of cases in such a way that we know how the inferred causes will behave in other cases. We call such an inference an inductive inference. We shall find ourselves obliged to modify the results of such an inference if something unexpected turns up in a further observation, because the character of the result is determined only by the individual form of the observations made. This conditional knowledge of causes, however, is completely sufficient for practical life, claims the metaphysical realist.

[ 36 ] Inductive reasoning is the methodological basis of modern metaphysical realism. There was a time when it was believed that something could be developed from concepts that was no longer a concept. It was believed that the metaphysical real beings that metaphysical realism requires could be recognized from the concepts. Today, this kind of philosophizing is a thing of the past. Instead, however, one believes that from a sufficiently large number of facts of perception one can deduce the character of the thing in itself that underlies these facts. As in the past from the concept, so today we believe we can develop the metaphysical from the perceptions. Since we have the concepts before us in transparent clarity, we believe that we can also deduce the metaphysical from them with absolute certainty. The perceptions are not equally transparent. Each subsequent one presents itself somewhat differently from the previous ones of the same kind. Basically, therefore, what is deduced from the previous ones is modified somewhat by each subsequent one. The form that is obtained in this way for the metaphysical can therefore only be called a relatively correct one; it is subject to correction by future cases. The metaphysics of Eduard von Hartmann, whose motto on the title page of his first major work is: "Spekulative Resultate nach induktiv naturwissenschaftlicher Methode. "

[ 37 ] The form that the metaphysical realist currently gives to his things in themselves is one obtained through inductive conclusions. He is convinced of the existence of an objectively real context of the world in addition to the "subjective" one recognizable through perception and concept through considerations about the process of cognition. He believes that he can determine the nature of this objective reality through inductive conclusions from his perceptions.

Addition to the new edition (1918)

[ 38 ] For the unbiased observation of experience in perception and concept, as has been attempted to be described in the preceding remarks, certain ideas that arise on the ground of the observation of nature will always be disturbing. One says to oneself, standing on this ground, that colors from red to violet are perceived by the eye in the light spectrum. But beyond the violet there are forces in the radiation space of the spectrum to which no color perception of the eye corresponds, but a chemical effect; likewise, beyond the limit of red effectiveness there are radiations that have only thermal effects. Considerations directed towards such and similar phenomena lead to the view that the scope of the human world of perception is determined by the scope of man's senses, and that he would have a completely different world before him if he had other senses in addition to his own, or if he had other senses at all. Whoever indulges in the extravagant fantasies to which, in this direction, the brilliant discoveries of recent natural science in particular offer a quite seductive inducement, may well come to the conclusion: Only that which is capable of acting on the senses formed out of his organization falls into man's field of observation. He has no right to regard what he perceives, limited by his organization, as somehow decisive for reality. Every new sense would have to present him with a different picture of reality. - All this is, within the appropriate limits, a perfectly justified opinion. But if someone allows himself to be misled by this opinion in the unbiased observation of the relationship between perception and concept asserted in these explanations, he obstructs the path to a world and human knowledge rooted in reality. Experiencing the essence of thought, i.e. the active elaboration of the conceptual world, is something quite different from experiencing something perceptible through the senses. Whatever senses man might still have: none would give him a reality if he did not think through what he perceives through them with concepts; and every sense of whatever kind, thus penetrated, gives man the possibility of living within reality. The fantasy of the possible completely different perceptual image with other senses has nothing to do with the question of how man stands in the real world. One must realize that every perceptual image receives its form from the organization of the perceiving being, but that the perceptual image permeated by the experienced thinking observation leads the human being into reality. It is not the fantastic imagination of how a world should look different to others than the human senses that can cause man to seek knowledge about his relationship to the world, but the insight that each perception only gives a part of the reality it contains, that it therefore leads away from its own reality. This insight is then accompanied by the other insight that thinking leads into the part of reality hidden by the perception itself. The unbiased observation of the relationship described here between perception and the concept developed by thinking can also be disturbed if, in the field of physical experience, the necessity arises to speak not at all of directly vividly perceptible elements, but of non-visible quantities such as electric or magnetic lines of force and so on. It can appear as if the elements of reality that physics speaks of have nothing to do with either the perceptible or the concept developed in active thinking. But such an opinion is based on self-deception. First of all, it is important that everything worked out in physics, insofar as it does not represent unjustified hypotheses that should remain excluded, is gained through perception and concept. What appears to be non-visual content is in fact placed in the field in which the perceptions lie by the physicist's correct cognitive instinct, and it is thought of in terms with which one operates in this field. The strengths of force in the electric and magnetic fields and so on are, by their very nature, not obtained by any other process of cognition than that which takes place between perception and concept. - An increase or a different organization of the human senses would result in a different image of perception, an enrichment or a different organization of human experience; but real knowledge would also have to be gained through the interaction of concept and perception. The deepening of cognition depends on the powers of intuition (see page 95) that manifest themselves in thinking. In the experience that takes shape in thinking, this intuition can delve into deeper or less deep undergrounds of reality. By expanding the perceptual image, this immersion can receive stimuli and in this way be indirectly promoted. However, never should diving into the depths, as the attainment of reality, be confused with the confrontation of a wider or narrower perceptual image, in which always only half a reality, as it is conditioned by the cognitive organization, is present. He who does not lose himself in abstractions will see how the fact also comes into consideration for the knowledge of the human being that for physics in the field of perception elements must be explored for which a sense is not directly attuned as for color or sound. The concrete nature of man is not only determined by that which he confronts as direct perception through his organization, but also by the fact that he excludes others from this direct perception. Just as the unconscious state of sleep is necessary to life alongside the conscious state of wakefulness, so the self-experience of man is necessarily surrounded by a - much larger even - circle of non-sensually perceptible elements in the field from which the sensory perceptions originate. All this is already indirectly expressed in the original presentation of this writing. The author has added this expansion of the content here because he has found that some readers have not read carefully enough. - It should also be borne in mind that the idea of perception, as it is developed in this paper, must not be confused with that of external sense-perception, which is only a special case of it. It will be seen from what has already been said, but even more so from what will be said later, that here everything that approaches man sensually and spiritually is understood as perception before it is grasped by the actively developed concept. In order to have perceptions of a mental or spiritual nature, senses of the usual kind are not necessary. One could say that such an extension of the usual use of language is inadmissible. But it is absolutely necessary if one does not want to be fettered in certain areas by the use of language in the expansion of knowledge. Whoever speaks of perception only in the sense of sensory perception does not arrive at a concept that is useful for knowledge, even through this sensory perception. One must sometimes extend a concept so that it receives its appropriate meaning in a narrower field. One must also sometimes add something else to what is first thought in a concept, so that what is thought in this way finds its justification or also justification. Thus on page 107 of this book we find the following statement: "The concept is therefore an individualized concept." It was objected to me that this was an unusual use of the word. But this use of words is necessary if we want to understand what imagination actually is. What would happen to the progress of knowledge if the objection was made to everyone who is put in the position of having to correct concepts: "That is an unusual use of words."